Please help :(( Ca + 2H2O --> Ca(OH)2 + H2 If 25.0 g water reacts with excess calcium solid,
a) Find grams of hydrogen gas produced
b) Find moles of Ca(OH)2 made.

0.7 moles of Ca(OH)₂ are produced.

Mass of hydrogen gas = 1.4 g

Explanation:

Given data:

Mass of water = 25.0 g

Mass of hydrogen gas produced = ?

Number of moles of Ca(OH)₂ formed = ?

Solution:

Chemical equation:

Ca + 2H₂O    →     Ca(OH)₂ + H₂

Number of moles of water:

Number of moles = mass/molar mass

Number of moles = 25.0 g/ 18 g/mol

Number of moles = 1.4 mol

Now we will compare the moles of water with hydrogen:

                 H₂O         :          H₂

                  2             :          1

                1.4             :          1/2×1.4 = 0.7 mol

Mass of hydrogen gas produced:

Mass = number of moles × molar mass

Mass = 0.7 mol × 2 g/mol

Mass = 1.4 g

Now we will compare the moles of water and Ca(OH)₂

                   H₂O          :          Ca(OH)₂

                      2            :            1

                   1.4             :           1/2×1.4 = 0.7 mol

Thus, 0.7 moles of Ca(OH)₂ are produced.